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DATA OF THE NORTH AMERICAN APPLICATION. RELATED This application claims priority to the
Provisional Application North American Serial Number
60 / 194,703, filed April 5, 2000. FIELD OF THE INVENTION The present invention generally relates to a concrete plant. More particularly, the present invention relates to a portable concrete plant. BACKGROUND OF THE INVENTION Concrete is used in the construction of a variety of different structures such as buildings, bridges and roads. Typically, the concrete is prepared in the form of ready-mix concrete in a central location and then transported via ur. truck to a location where ready-mixed concrete is to be used. While this technique allows larger batches of ready-mix concrete to be produced, the quality of the concrete varies significantly depending on the distance between the location where the ready-mix concrete is prepared and the location where the ready-mixed concrete is used, since ready-mixed concrete is begins the curing process as soon as it is ready: ». As such, it is often necessary to add onents to ready-mix concrete that either slow or speed up the curing process.
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used. The Weisbrod system is particularly suitable for use with the preparation of relatively small quantities of ready-mix concrete. One of the important onents of a system that prepares pre-mixed concrete is the slurry mixer that mixes water, cement and other onents in a cement slurry, which can then be mixed with rock and sand to produce ready-mix concrete. Brown et al., U.S. Patent No. 4,588,299, and Strehlow, U.S. Patent No. 4,865,457, each disclose a slurry mixer having a horizontally oriented mixing region. Milek, U.S. Patent No. 6,030,112, discloses a batch mixer of cement slurry having an elongated configuration. The batch mixer of cement slurry has a duct with a curved bottom. A belt-type worm conveyor is mounted in the conduit parallel to a shaft axis. The rotation of the endless screw conveyor not only mixes the onents together but also transports the mixed onents to the conduit discharge port. Williams, U.S. Patent No. 5,718,508, discloses a self-cleaning slurry blender having a cylindrical shape with a feed screw extending therethrough to mix the onents together and
to transport the mixed cement slurry to the cement slurry outlet, Macauley et al., U.S. Patent No. 5,427, 448, discloses a twin screw grout mixer, where the screws are oriented parallel to each other. Hood, U.S. Patent No. 5,908,240, discloses a tank-type grout mixer having two sets of blades rotatably mounted therein. The paddles cause the mixture to be removed in the upward direction along the side walls of the tank. Brown, U.S. Patent No. 4,963,031, also discloses a tank-type grout mixer. None of the prior art references or describes a portable concrete plant that is suitable for producing premixed concrete in proportions between
75 and 200 cubic yards per hour, as is typically required for ercial applications, The precise control of rock and sand flow also plays an important role in the preparation of ready-mixed concrete with consistent characteristics. Bush, U.S. Patent No. 4,976,378, discloses a pallet-type feeding dosing system. The Bush device includes four paddles that are rotatably mounted in an enclosure. The rotation of the pallet supplies a predetermined weight of material.
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BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a portable concrete plant for preparing ready-mix concrete, near a location where ready-mix concrete is to be used. The portable concrete plant includes a frame, a rock storage region, a sand storage region, a cement storage region, a water storage region, a slurry mixer, a rock conveyor system and a system sand conveyor. The frame has at least one set of wheels attached thereto, to support the frame above an earth surface and allow the frame to be moved along the ground surface. The cement storage region stores cement and is attached to the frame. The cement storage region has a cement entry port and a cement exit port. The sand storage region stores sand and is attached to the frame. The sand storage region has a sand inlet port and a sand outlet port. The rock storage region stores rock and is attached to the frame. The rock storage region has a rock entrance port and a rock exit port. The water storage region stores water and is attached to the frame. The water storage region
It has a water inlet port and a water outlet port. The grout mixer is attached to the frame. The slurry mixer has an inlet port of the slurry mixer and an outlet port of the slurry mixer. The cement outlet port and the water outlet port are operably connected to the inlet port of the slurry mixer. The grout mixer prepares a slurry of cement and water. The first conveyor system is attached to the frame. The first conveyor system receives the rock from the rock exit port and the sand from the sand exit port and transports the rock and sand to an exit port of the system. The second conveyor system is attached to the frame. The second conveyor system receives the cement slurry from the outlet port of the slurry mixer and transports the cement slurry to the output port of the system. The first conveyor system and the second conveyor system are crossed near the exit port of the system, to cause the cement slurry to be mixed with the sand and rock for the preparation of ready-mix concrete. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a first side view of a portable concrete plant according to the present
invention. Fig. 2 is a top view of the portable concrete plant and Íps conveyor systems for material feed. Fig. 3 is a side view of the cement storage region and the mixing region. Fig. 4 is a schematic view of a dust collection system of the portable concrete plant. Fig. 5 is a side view of a sand flow dosing device for use in the portable concrete plant. Fig. 6 is a sectional view of the sand flow dosing device, taken along a line 6-6 in Fig. 5. Fig. 7 is a top view of a slurry mixer for the plant of portable concrete Fig. 8 is a sectioned view of the grout mixer taken along a line 8-8 in Fig. 7 Fig. 9 is a sectional view of the grout mixer taken along a line 9- 9 in Fig. 8 Fig. 10 is a schematic illustration showing the material flow paths in and out of the slurry mixer. Fig. 11 is a sectioned view of a concrete discharge device for the plant
portable concrete. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The present invention is directed to a portable concrete plant, as illustrated more clearly at 10 in Fig. 1. The portable concrete plant 10 is capable of producing between about 75 and 200 cubic yards of ready-mix concrete per hour. The portable concrete plant 10 is suitable for use near a location where ready-mix concrete is to be used. The portable concrete plant 10 in this way reduces the cost of transportation of ready-mix concrete to the location where the concrete will be used. The portable concrete plant 10 also improves the quality of the concrete by eliminating wet or dry loads that are caused by variations in the time of supply to the location, where ready-mix concrete will be used. By reducing these variations, the qualities of the finished concrete are improved, such as strength. It is possible to use the portable concrete plant
10 in a variety of locations with only minimal preparations to locations such as the provision of a relatively flat and stable surface. The portable concrete plant 10 has a low center of gravity, which makes the portable concrete plant 10 stable for use
on a variety of ground surfaces. The portable concrete plant 10 generally includes a frame 20, a material storage region 22, a material mixing region 24 and a mixed material supply region 26 that are each mounted to the frame 2C. The frame 20 is preferably manufactured to extend around the components of the portable concrete plant 10. The jiel frame components 20 are selected to maintain the components of the portable concrete plant 10 in a position. fixed, not only during the use of the portable concrete plant 10, but also during the transport of the portable concrete plant 10 to a location where the portable concrete plant 10 is to be used. The frame 20 is preferably selected with a width, length and height which allows the portable concrete plant 10 to comply substantially with all the regulations applicable to the "size of the road, such that the portable concrete plant 10 can be transported on a significant percentage of the roads without obtaining special permits. For most applications, the width is less than approximately 102 inches, the length is less than approximately 61 feet and the height is approximately 13 feet 6 inches
The frame 20 of preference includes a removable gooseneck 18 which facilitates the attachment of the portable concrete plant 10 to a truck, for transportation of the portable concrete plant 10 to a desired location of use. The gooseneck 18 is preferably removed during the operation of the portable concrete plant 10 to reduce a distance that the ready-mix concrete must be transported to the outlet port of the system. The frame 20 is supported by at least one set of wheels 21 which allows the portable concrete plant 10 to be easily transported to a desired location of use. The number of wheel assemblies 21 and the number of wheels in each set of wheels 21 is selected based on the applicable weight limitations. For most applications,. The portable concrete plant 10 has three sets of wheels 21 that include two wheels on each side of the frame 20, Depending on the roads on which the portable concrete plant 10 is transported, it is also possible to include a set of wheels ( not shown) attached to the end of the frame 20 opposite the neck of the goose 18. This extra set of wheels is preferably operably attached to the frame 20 to allow the wheels to be lowered when needed and retracted when they are not needed. The movement of the extra set of wheels
Preference is controlled through the connection to a hydraulic system, which is described in more detail in the following. The sides of the portable concrete plant 10 are preferably covered by tarpaulins 23 which protect the components of the portable concrete plant 10 during cold weather operations and facilitate the heating of the components to prevent freezing of the materials in the plant of portable concrete. The tarps 23 also protect the portable concrete plant 10 during transport or while it is not in use. A heat exchanger (not shown) can be positioned under the tarpaulin 23 to heat the components of: the portable concrete plant 10 during the cold weather to prevent freezing of the components used in the portable concrete plant 10. The tarps 23 are preferably retractable to a relatively small region near the top of the frame when the parrots 23 are not in use, to provide access to the < j > s components of the portable concrete plant 10. A person of ordinary skill in the art will appreciate that a variety of materials are suitable for use in the manufacture of the tarpaulin 23. A person of ordinary skill in the art will also appreciate that a variety of mechanisms are suitable for either automatically or manually moving the canvases 23 from an extended position to the retracted position,
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Near the lower portion 42, the storage region of cement 30 has a flow control mechanism 44 which controls the flow of cement from the cement storage region 30 as schematically illustrated in Fig. 3. The region of cement storage 30 includes four flow control mechanisms 44. The use of the four flow control mechanisms 44 improves the ability to accurately control the proportion by which cement is supplied from the cement hopper 40. The utilization of four flow control mechanisms 44 also improves the uniform load of the vane system 130 in the slurry mixer 120 and thus reduces the large torsional differential indices which can lead to potential damage to the components in the slurry mixer 120 The use of the four flow control mechanisms 44 also improves the ability to quickly load cement into the mixer. grout 120 In particular, approximately 5,640 pounds of cement, which are needed to prepare 10 yards of ready-mix concrete in a mixing protocol of
6 bags are loaded into the grout mixer 120 in less than 30 seconds and preferably about 15 seconds. The flow control mechanism 44 preferably
includes a valve valve rotatably mounted. However, a person of ordinary skill in the art will appreciate that other valve mechanisms can be used to control the flow of cement from the cement hopper 40. The operation of the flow control mechanism 44 is preferably controlled by the operable joint. to a hydraulic system in the portable concrete plant 10, which is described in more detail herein. Alternatively, it is possible to control the operation of the flow control mechanism using an electric or pneumatic control system. The cement hopper 40 is preferably mounted to the frame 20 using a load cell 46 which allows the weight of the cement hopper 40 to be monitored on a continuous basis. The continuous monitoring of the weight of the cement hopper 40 improves the ability to accurately add cement during the concrete preparation process. Such a system is typically referred to as a load loss system in pese. To improve the ability to produce permanent flow of the cement from the cement hopper 40, the cement storage region 30 preferably includes a vibrator 48 operably connected thereto. To minimize the noise associated with the drawer vibrator 48, as well as the natural wear of the components of the cement storage region 30, the drawer vibrator 48 of
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preference is only activated while the flow control mechanism 44 is in operation. A dust collection system 50 is preferably provided in the cement storage region 30 to collect the dust that is generated by moving the cement into and out of the cement storage region 30, as schematically illustrated in FIG. Fig. 4. The dust collection system 50 initiates a series of filter cartridges 51 in which the powder is collected. The total surface area provided by the filter cartridges 51 is between 500 and 2000 square feet and preferably approximately 1000 p: Les squares. At selected intervals the powder is removed from the filter cartridges 51 and then transported to the mixing region of material 24 with an auger 52. This recycling system minimizes the amount of meal powder that must be discarded and prolongs the life of the waste. filter cartridges 51. The dust collection system 50 also preferably includes a port (not shown) that provides operators with the ability to inspect: the filter cartridges 51 to determine when it is necessary to replace the filter cartridges 51 The port also provides the ability to easily enter the filter cartridges 51 when it is necessary to replace the filter cartridges 51. The cement is preferably supplied to the
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cement storage region 30 from a bulk, auxiliary cement storage tank car (not shown) that is operably connected to the cement storage region 30 with a cement transfer line (not shown). The auxiliary bulk cement storage tank car is operably connected to the portable concrete plant 10 using hydraulically operated control valves, allowing the cement flow to be controlled from a control room at the ccoonnccrreetto plant ppoorrttaattiill 1100 .. The transfer of cement from bulk cement storage tanks, auxiliary, is preferably carried out using conventionally known techniques, such as, with air blowing. The sand storage region 32 includes a sand hopper 60 having a substantially open upper portion 62 that tapers down to a lower portion 64. The hopper 60 preferably has a storage capacity of approximately seven cubic yards. The substantially open upper portion 62 allows the sand to be replenished in the sand hopper
60. Near the lower portion 64, the sand storage region 32 has a flow control mechanism 66 that controls the flow of sand from the sand storage region 32 The flow control mechanism 66 is preferably a metering valve of palette
68, as illustrated in Figs. 5 and 6. The vane dosing valve 68 reduces bridging of the material in the sand hopper 60 and provides the ability to individually control the proportions in which the materials are supplied from the sand hopper 60. The Pallet dosing 68 generally includes two elements, the rotatable vane element 70 and the gate element 70. The rotatable vane element 70 has a plurality of vanes 74 extending therefrom. The rotatable vane element 74 is oriented for rotate parallel to the direction in which the sand is falling out of the sand hopper 60. The gate element 72 is rotatable between a closed position, oriented adjacent the rotatable vane element 70 and an open position. When in the closed position, the rotatable vane member 70 and the gate element 72 substantially prevent sand flow from the sand hopper 60. When the gate member 72 rotates from the closed position to the. open position as indicated by arrow 76, the sand is allowed to flow from the sand hopper 60 The rotation of the rotatable vane element 70 in this way improves the ability to produce a uniform sand flow rate The change in the proportion to which the rotatable vane element 70 is rotated, allows
the proportion of sand flow is changed. The positioning of the gate element 72 in the intermediate positions e; tre the open position and the closed position also allows the sand flow rate to be varied. The sand storage region 32 is preferably mounted to the frame 20 using a load cell 77 which allows < : 1 weight of sand from sand hopper 60 is monitored on a continuous basis. The continuous monitoring of the weight of the sand bed 60 improves the ability to accurately add sand during the concrete preparation process. The continuous monitoring of the weight of sand in the sand hopper 60 also provides the operator with an indication of when it is necessary to replenish the sand in the sand hopper 60. To improve the capacity to produce permanent flow of the sand from the hopper of sand 60, the storage region of sand:? 32 preferably includes a vibrator 78 operably attached thereto. To minimize the noise associated with the drawer vibrator 78, as well as the natural wear on the components of the sand storage region 32, the drawer vibrator 78 is preferably only activated while the flow control mechanism is in operation. 66. The rock storage region 34 includes a
rock hopper 80 having a substantially open upper portion 82 tapering downward to a lower portion 84, as more clearly illustrated in Fig. 1. The hopper 80 preferably has a storage capacity of approximately seven cubic yards. The substantially open upper portion 82 allows the rock to be replenished in the rock hopper 80. Near the lower portion 84, the rock storage region 34 has a flow control mechanism 86 that controls the rock flow of the region. Rock storage 34. The flow control mechanism 86 preferably includes a pair of gates which are pivotally mounted near the lower portion 84. Rotating the gates to a closed position prevents the rock from flowing out of the rock. the rock hopper 80. Rotating the gates to an open position allows the rock to flow out of the rock hopper 80. The rotation of the gates between the open position and the closed position is preferably controlled by a hydraulic cylinder ( not shown). The metering valve preferably includes a flow control that allows the slow opening of the valve to promote controlled free fall and rapid closing of the valve to promote precise reach of the target material weight. The rock hopper 80 is mounted to the frame 20
using a load cell 90 that allows the weight of the rock hopper 80 to be obtained in a continuous base. The continuous monitoring of the pesb of the rock hopper 80 improves the ability to accurately add rock during the concrete preparation process. The continuous monitoring of the rock weight in the rock hopper 80 also provides the operator with an indication of when it is necessary to replenish the rock in the rock hopper 80. To improve the capacity to produce permanent flow of the rock from the hopper of rock 80, the rock storage region 34 preferably includes a vibrator 92 operably linked thereto. To minimize the noise associated with the drawer vibrator 92, as well as the natural wear on the components of the rock storage region 34, the cavalry vibrator 92 is preferably only activated while the flow control mechanism 86 It is in operation. The water storage region 36 includes a substantially enclosed container 110 having a capacity of between approximately 100 gallons and 500 gallons. The portable concrete plant 10 has a weight cell 112 that is attached to the water storage container 110. The weight cell 112 allows the weight of the water storage container 110 to be monitored continuously to precisely control the water supply in the container.
cement preparation process. The weight cell 112 also provides the operation with an indication of when it is necessary to refill the water storage container 110. As an alternative to manually monitor the water level in the water storage container 110, the water level can be automatically control to refill the water storage vessel 110 from a water source. Depending on the site where the portable concrete plant 10 is used, the water source typically is either a tank car filled with water or the union to a municipal water supply, such as through a fire hydrant, the region of blended material 24 includes a grout mixer 120 having a generally cylindrical shape with a side wall 122 and a base wall 124 enclosing a lower end of the grout mixer.
120, as illustrated more clearly in Figs. 7-9. A supply channel 126 is provided in the base wall 124 for conveying the cement slurry out of the slurry mixer 120. A supply bit 128 is rotatably mounted in the supply channel 126. The rotation of the supply bit 128 carries the cement slurry out of the supply channel 126. The 1-slot 120 mixer has a system of
paddles 130 rotatably mounted therein, for mixing together the materials is placed in the slurry mixer 120. The rotation of the paddle system 130 is preferably controlled by a motor mounted on the upper part 131. The use of the motor mounted on the Top 131 I eliminated! the need to use high maintenance shaft seals and allows the supply auger 128 to extend into the full bottom of the slurry mixer 120. This configuration also improves the ability to perform the end-of-day cleaning on the mixer components. slurry 120. Vane system 130 has a self-cleaning configuration to facilitate removal of all cement slurry from slurry mixer 120 at the end of each work day. The self-cleaning capability in this way minimizes the time and effort required to clean the slurry mixer 120 and ensures complete removal of the grout from the slurry mixer 120. The vane system 130 includes a central element 132 and the element of rotation 134 extending from the central element 132 close to the side wall 122. The lower mixing elements 140 extend upwardly the lower rotation element 134, such that the cleaning ends 142 of the lower mixing elements 140 they slide on a deck
top 145 to thereby clean the cement slurry mixture from the top cover 145. Similarly, the top mixing elements 146 extend downwardly from the top cover 145, such that the cleaning ends 148 of the mixing element upper 146 slide on an upper surface 150 of the lower element 134, to thereby clean the cement grout mixture from the lower element 134. The rotation of the lower rotating elements 134 causes the lower mixing elements 140 to move between the upper mixing elements 146 and in this way cause the water, cement and other components placed in the slurry mixer 120 to be mixed together to produce a cement slurry. The slurry mixer 12 allows the water, cement and other components to be mixed in less than 60 seconds and preferably between about 15 and 30 seconds. The slurry mixer 120 of the present invention promotes a high degree of mixing, such that almost all cement particles are coated with water. The components in the slurry mixer 120 are preferably all coated with plastic to reduce the adhesion of the cement slurry to the components of the slurry mixer 120. The use of the plastic coated components in the slurry mixer 120
it also reduces rotational friction and decreases the energy consumption associated with the operation of the slurry mixer
120. The plastic-coated components in the grout mixer 120 also improve the ability to accurately transfer the grout of the grout mixer 120. Additionally, the use of the plastic coated components in the grout mixer 120 improves the ability to clean the grout mixer 120 at the end of the day. The upper mixing elements 146 are misaligned from the lower mixing elements 140, as illustrated more clearly in Figs. 7 and 8, such that as the lower rotation element 134 is rotated, the lower mixing elements 140 pass between the upper mixing elements 146. ' The upper mixing elements 146 and the lower mixing elements 140 can be configured, such that the upper mixing elements 146 and the lower mixing elements 140 scrape against each other to reduce the accumulation of cement slurry. in the upper mixing elements 146 and in the lower mixing elements 140. The lowermost, outer mixing element 140 preferably slides along the side wall 122, as the lower rotation element 134 is rotated,
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to thereby reduce the accumulation of cement slurry in the side wall] 122. The slurry mixer 120 preferably includes a sludge mixer 149 collection system, which captures the dust that is generated during the mixing process. cement grout, as illustrated in Fig. 3. Depending on the size of the portable concrete plant 10, the grout mixer 149 collection system can collect and dispose of the dust collected therein or recycle the powder to the slurry mixer 120. Since the amount of dust generated in the slurry mixer 120 typically is not large enough to guarantee the cost associated with the capture and recycling of the powder, the dust collected in the dust collection system 149 of the grout mixer is typically discarded. The cement slurry is pumped from the slurry mixer 120 to a discharge boot 150 using a cement slurry pumping system 152, as illustrated more clearly in Fig. 1. While it is possible to use a single slurry pump of cement 154 in the cement slurry pumping system 152, the cement slurry pumping system 152 preferably includes a series of cement slurry pumps 154 which are connected in parallel. The grout pumps 154 used in conjunction with
the present invention, preferably have a multiple tube configuration. By using several cement grout pumps 154 in parallel, the ability to precisely control the proportion at which the grout is supplied to the discharge boot 150 is improved because each grout pump 154 only pumps one. relatively small amount of cement slurry. Alternatively, the proportion of cement slurry flow can be adjusted by decreasing or increasing the number of cement pump pumps 154 that are simultaneously used. The cement slurry pump system 152 preferably includes a manifold 156 that facilitates the substantially uniform supply of the cement slurry to the slurry pumps 154. The cement slurry pumping system 152 also preferably includes a centrifugal pump 158 which facilitates the transfer of the cement slurry from the discharge boot 150, to through manifold 156 and slurry pumps 154. Centrifugal pump 158 preferably operates at a rate of about 1,800 revolutions per minute. The use of the centrifugal pump 158, in addition to the multiple tube type grout pumps 154, improves the efficiency of the grout pumps 154, because the centrifugal pump 158 ensures that the grout pumps 154 have the tube chambers
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multiple substantially filled. The portable concrete plant 10 has the capacity to use aggregates that control and / or improve the characteristics of ready-mix concrete, prepared by the portable concrete plant 10. Examples of suitable aggregates are air entrainment materials, conventional and non-corrosive accelerators , and plasticizers. Some of these aggregates can be added to the slurry mixer 120, while others can be used in other locations such as in the dry material conveyor 190 or in the discharge boot 150. The operation of the components of the portable concrete plant 10 is preferably controlled with a hydraulic system. The use of the hydraulic system is preferable because the hydraulic systems have the capacity to produce high levels of forces in a relatively safe and reliable manner. The hydraulic system also allows infinitely variable speed control, to which the components are operated, such as the conveyor belt. A person of ordinary skill in the art will appreciate that it is possible to use alternative mechanisms to control the operation of the components of the portable concrete plant 10 using the concepts of the present invention.
The hydraulic system is preferably operated at a pressure of approximately 2,000 pounds per square inch. The use of this moderate pressure level improves the safety of the components when compared to high pressure systems operating at high pressures of 5,000 pounds per square inch or more. This level of moderate pressure also results in wear on the pump head used to generate the pressure used in the hydraulic system. The pump heads used in conjunction with the hydraulic system preferably have a variable flow configuration that allows the pump heads to lower in speed when oil is not needed. This feature also reduces wear on the components of the hydraulic system. Each of the components that is operated by the hydraulic system preferably has a partial deviation configuration that allows the component to operate at a very slow speed of rotation even when the component is not activated. By using the deflection circuit, the large initial forces that are imparted when the rotation is initially started are substantially reduced. The hydraulic system is preferably driven by an internal combustion engine 162 that is mounted to the frame 20. The incorporation of the internal combustion engine 162 in the portable concrete plant 10 allows the
Portable concrete plant 10 is operated without considering the proximity of the convenient service to the location where the portable concrete plant 10 will be used. A preferred internal combustion engine 162 for use with the portable concrete plant 10 is a diesel engine having a power in horsepower in the range of 150 to 300 and preferably approximately 220. An internal combustion engine 162 particularly suited for use with the portable concrete plant 10 is manufactured by Caterpillar Co. A person of ordinary skill in the art will appreciate that it is possible to operate the operation of portable concrete plant 10 with a variety of other techniques, such as by means of electricity. The internal combustion engine 162 is preferably removably mounted to the frame 10 in a slide 163 which allows the unit to be easily disengaged from the portable concrete plant 10 to perform the maintenance or repair of the internal combustion engine 162. To operate the operation of the internal combustion engine 162, the portable concrete plant 10 preferably includes an onboard fuel storage tank 164. The onboard fuel storage tank 164 has a capacity of between approximately 50 gallons and 200 gallons, and preferably of approximately 100 gallons. Also operably linked to the combustion engine
internal 162 is an air compressor (not shown) to provide compressed air, as required, for the operation of certain components in portable concrete plant 10. For example, compressed air can be used to transport cement from the tank car storage of bulk cement, auxiliary, to the cement hopper 40. The internal combustion engine 162 preferably also includes a high power output AC alternator.
(not shown) operably connected thereto, to operate the operations of the electrically operated components in the portable concrete plant 10. The high power output AC alternator facilitates the operation of the portable concrete plant 10 without considering the availability of electric power, where it is desired to use the portable concrete plant 10. For example, the alternator can be used to provide power for a computer in the control room 170. The portable conlcrete plant 10 preferably includes a heat exchanger 168 mounted to it. The heat exchanger 168 cools the hydraulic oil used in the hydraulic system 160 while heating the water that is used in the preparation of the cement slurry. Water heating is particularly useful when the portable concrete plant 10 is used in climates
cold, because the heated water reduces the need to add acceleration or retardation aggregates during the concrete preparation process. The cooling of the hydraulic oil in the hydraulic system also increases the efficiency of the hydraulic system. The portable concrete plant 10 preferably includes a control room 170. The control room 170
• provides continuous monitoring of the conditions in each of the components of the portable concrete plant 10. 10 The control room 170 allows an operator to adjust almost all the parameters related to the operation of the
• portable concrete plant 10. Control room 170 is preferably substantially enclosed to protect controls from damage by environmental factors such as
15 as rain or corrosion by materials that are processed in the portable concrete plant 10. The operation of the portable concrete plant 10 is preferably controlled by at least one computer (not shown) located in the control room 170. The computer 20 preferably allows the individual components of the portable concrete plant 10 to be simultaneously controlled. A person of ordinary skill in the art will also appreciate that alternate methods are possible to control the operation of the portable concrete plant 10. 25 The portable concrete plant 10 preferably
they include levelers 180 that allow the portable concrete plant 10 to be maintained in a level orientation without considering the conditions of the location where the portable concrete plant 10 is to be used. The levelers 180 in this way avoid or substantially reduce the need of excavating at the proposed site of use, Preferably, there is a series of six levelers 180, with the levelers that are spaced around the frame 10. The levelers 180 are extendable in varying degrees of the frame 20, using an operable joint to the hydraulic system . Bulldozers 180 preferably have a range of motion of up to 24 inches. To additionally stabilize the portable concrete plant 10, a plate (not shown) can be placed below one or more of the levelers 180. When they are in the extended position, the conveyor modules 184 move independently of each other, so that the conveyor modules 184 remain in a substantially paphaleous relationship, but in such a way that the conveyor modules 184 are aligned with the hopper into which the material is to be fed. The portable concrete plant 10 has a dry material conveyor 190 for transferring the ready-mix concrete components to the concrete mixing truck. The dry material conveyor 190 passes under
of the sand flow control mechanism 66 and the rock flow control mechanism 86, so as to receive the sand and rocks from the sand hopper 60 and the rock hopper 80, respectively. The dry material conveyor 190 transports the sand and the rock to the discharge boot 150,
The rate of velocity at which the dry material conveyor 190 operates is adjustable to allow precise control of the proportion at which the sand and rock are delivered to the discharge boot 150. The dry material conveyor 190 preferably includes two speeches. A first section 191 extends in a substantially horizontal direction beneath the sand hopper 64, the rock hopper 84 and the slurry mixer 120. A second section 192 is positioned near one end of the first section 191 which is opposite the sand hopper 64. The second section 192 is oriented at an angle to transport the dry material from the first section 191 to the boot 150. Near the intersection of the first section 191 and the second section 192 is a protective cover 191 which extends over the first section 191 and the second section 192 to prevent sand and stones from falling out of the dry material conveyor 190. The protective cover 195 may also include a door (not shown) pivotally mounted near an outlet of the same to reduce
additionally the power for sand and rock to fall out of the dry material conveyor 190. Additionally, the dry material conveyor 190 may include side covers (not shown) that are partially positioned on the dry material conveyor 190 near the intersection of the first section 191 and the second section 192 to prevent sand and rock from falling out of the dry material conveyor 190. The discharge boot 150 preferably extends from the front end of the portable concrete plant 10, as shown in FIG. more clearly illustrated in Figs. 1 and 2. However, a person of ordinary skill in the art will appreciate that the discharge boot 150 may also extend from the rear end or sides of the portable concrete plant 10 utilizing the concepts of the present invention. The discharge boot 150 allows adjustment to compensate for different concrete mixers, so that the loading height can be varied. By changing the height of the levelers the different heights of the mixer truck are compensated. Due to the position of the concrete discharge boot 150, it is not necessary to excavate a loading pit. One end of the dry material conveyor 190 that is attached to the discharge boot 150 is preferably pivotally mounted so that a height of the conveyor
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Discharge 190 can be adjusted depending on the height of the concrete mixing trucks. The discharge boot 150 receives the rock and sand from the dry material conveyor 190 and the cement slurry from the slurry line 155. The discharge boot 150 imparts a slurry movement to the cement slurry, rock and concrete. sand, as these components are fed into the drum of the concrete mixer truck, as illustrated more clearly in Fig. 11. In this technique, the cement grout is covered by rock and sand to promote uniform mixing of the cement grout with the rock and sand. The spiral movement accelerates the loading of the rock and the cement grout, while preventing clogging of the discharge boot 150. The use of the < jie spiral loading also improves the quality of the mix by mixing the rock and sand to prevent segmentation of the material. The spiral movement imparted by the discharge boot 150 is preferably in the same direction as the spiral movement of the drum in the concrete mixing truck. The discharge boot 150 has a sleeve 194 extending therefrom. The position of the sleeve 194 with respect to the load boot 150 is adjustable, such that the sleeve 194 can be extended near the concrete mixing truck to minimize spillage. . The movement
of the sleeve 194 with respect to the discharge boot 150 is preferably controlled by a hydraulic cylinder 197. To additionally reduce the amount of dust and other materials emitted from the portable concrete plant 10, a drum sealing ring 193 extends from the sleeve 194. When the sleeve 194 is lowered into a feed funnel (not shown) in the concrete mixer truck, the drum sealing ring 193 sits substantially against a top surface of the feed funnel. Near the discharge boot 150, the portable concrete plant 10 preferably includes a rain gutter.
^ Aggregate feed 196. The aggregate feed chute 196 allows added aggregate, such as an accelerator or reinforcing fibers, to be added to ready-mixed concrete to thereby strengthen the concrete and avoid or reduce the need to use reinforcing bars. or steel mesh in the concrete. The location in which the reinforcing fibers are added to the other components of the ready-mixed concrete is important, because the addition of these fibers too early in the process presents problems with respect to the transport of the reinforcing fibers together with the rest of the fibers. the components, while the addition of the reinforcing fibers very ta :: of prevents dispersion in a
uniform reinforcement fibers in ready-mix concrete. Alternatively, the aggregate or reinforcing fibers can be fed onto the dry material conveyor 190 through the protective cover 195, as illustrated more clearly in Fig. 2r. The feeding of the reinforcing fibers in this manner is preferably performed through a conveyor 199, The portable concrete plant 10 of the present invention minimizes the environmental impact in the area surrounding the portable concrete plant 10, because the discharge boot 150 and the sleeve 194 allow the truck of concrete is loaded cleanly. In particular, the concrete loading system of the present invention eliminates or very at least substantially reduces dry stacking on the fins of the: nezclador in the drum of the concrete mixer truck. Additionally, the concrete loading system of the present invention eliminates or very at least substantially reduces the dust generated during the drum loading process of the concrete mixer truck. When the portable concrete plant 10 is used in very cold conditions, such as at a temperature of less than 20 ° F, the heat exchanger 168 included in the portable concrete plant 10 is not able to prepare a sufficient quantity of heated water which is used in a
complete day. For these situations, the portable concrete plant 10 also includes a complementary hot water system 200. The complementary hot water system 200 has a hot water generating component 202 and a hot water storage component 204. The generation component of hot water 202 is preferably powered by natural gas, propane and electricity. To improve the efficiency of the hot water generating component 202, this element is preferably placed in an insulated storage trailer 206, which allows the hot water generating component 202 to be transported to a location where the plant will be used. portable concrete 10. The hot water generating component 202 is capable of heating the water to a temperature between 100 ° and 200 ° F and preferably about 160 ° F. The hot water storage component 204 has sufficient capacity to store substantially all of the heated water that is used during a full day of ready-mix concrete preparation. The storage capacity of the hot water storage component 204 is preferably about 15,000 gallons. To facilitate transportation of the hot water storage component 204 together with the others
elements of the portable concrete plant 10, the hot water storage component 204 preferably includes three separate tank wagons, with each having a capacity of approximately 5,000 gallons. The hot water storage component 204 is preferably insulated to reduce the temperature loss caused by environmental factors. The use of the hot water storage component 204 in this manner allows the water to be heated xn. day before the hot water is used in the portable concrete plant 10. This system ensures that sufficient heated water is available. Controls of the flow rate of the components of the present invention allow the flow rates of the individual components to be controlled to an accuracy of more than 90 percent, preferably more than 99 per cent, and much more preferably greater than 99.95 percent The sand and gravel are preferably provided to the sand storage region 32 and the rock storage region 34 by a feed material conveyor system 182. The feed material conveyor system 182 preferably has a variable speed control to supply the components in a precise way.
The method of preparing and loading the ready-mix concrete into the drum of the concrete mixer truck maximizes the rate at which the components are mixed together, while preventing dry stacking in the drum of the concrete mixer truck. This procedure preferably causes the flow of sand to start or a few seconds before the rock flow begins. This technique produces a bed of sand in the mixer in which the rock is wrapped. Additionally, the flow of lighter materials and smoothies is started before the heaviest rock. The use of the technique of the present invention allows the drum to be changed :! of concrete is filled with enough grout, rock and sand to produce a batch of approximately 10 cubic yards of ready-mix concrete in approximately 60 to 90 seconds. The method of the present invention includes the ability to automatically compensate for the moisture level in the rock and sand. The basic mixing designs in the control system are selected based on rock and dry sand. The automatic sampling of the moisture level of the aggregates with a humidity level probe, as the materials are loaded into the storage hopper, makes it possible to control the system to automatically compensate for variations in the level of humidity.
humidity, to improve in this way the quality of ready-mix concrete, prepared by the portable concrete plant ÍO. In operation, the internal combustion engine 162 is started to create a pressure in the hydraulic system. The conveyor modules 184 are activated to fill the sand hopper 60 and the rock toL 80 with sand and rock, respectively. As the rock and sand are being filled into the sand hopper 60 and the rock hopper 80, respectively, the moisture content of these materials is measured so that the water added during the process can be adjusted to compensate for variations in the humidity in these materials. Next, the cement hopper 40 is filled from the bulk, auxiliary cement tank car, and the water storage container 110 is filled from the water supply. The engine 131 is activated to cause the vane system 130 to rotate in the grout mixer 120,
Water and cement are fed into the slurry mixer 120 from the water storage vessel 110 and the cement hopper 40, at a water to cement ratio of between 0.3 and 0.6, preferably between about 0.45 and 0.50, and much more preferably of about 0.48. The mixing in the slurry mixture 120 is continued until a slurry mixture is produced.
substantially homogeneous. The mixing preferably is continued for up to 60 seconds, preferably between approximately 10 seconds? and 30 seconds, and much more preferably for approximately 15 seconds. The supply bit 128 is then activated to transport the cement slurry out of the slurry mixer 120 and the slurry pumping system 152. The centrifugal pump 158 transports the slurry through the manifold 156 to the slurry pumps 154. The slurry pumps 154 are activated to transport the cement slurry through the slurry line 155 to the discharge boot 150. After each batch of slurry is poured from the slurry mixer 120, the slurry mixer 120 is filled with water and cement. Once the level of the rock, sand, cement and water in their respective storage regions is depleted to a specific level, the appropriate replenishment mechanism is activated to replenish the storage regions. The sand flow control mechanism 66 and the rock flow control mechanism 86 are activated to allow sand and rock to flow from the sand hopper 60 and the rock hopper 80, respectively, onto the material conveyor. dry 190. The dry material conveyor 190 is activated to transport the sand and rock to the dewatering boot 150.
target weights. The indistinct logic system in this manner allows the accuracy of the portable concrete plant 10 to increase over time. When the desired amount of ready-mix concrete has been prepared or the end of the day has been reached, the portable concrete plant 10 is cleaned. The water is fed into the slurry mixer 120 to wash any remaining cement slurry from the slurry mixer 120. The cleaning action provided by the upper cleaning elements 146 and the lower cleaning elements 140 remove any remaining cement slurry from the slurry 120. side wall 122 and the components of the vane system 130. Once all the components in the portable concrete plant 10 are cleaned to a desired level, the internal combustion engine 162 is stopped. When the complete project and the Portable concrete plant 10 must be moved to another location, the components are cleaned as described above. Any rock, sand, cement and water remaining in their respective storage regions are emptied to minimize the weight of the portable concrete plant 10. Then, the discharge boot 150 is lowered from an operating position to a storage position. and the gooseneck 18 is attached to the frame 20. The levelers 180 are raised to a storage position, so that the
centrifuge 158 conveyed the cement slurry through the manifold 156 and to the slurry pumps 154. The slurry pumps 154 were activated to transport the cement slurry to the discharge boot 150. Once the level of the rock, sand , cement and water in their respective storage regions, was depleted to a specific level, the appropriate replenishment mechanism was activated to replenish the storage regions. The sand flow dontrol mechanism 66 and the Rock 86 flow control mechanism were activated to allow sand and rock to flow from the sand hopper
60 and the rock hopper 80, respectively, on the dry material conveyor 190. The dry material conveyor 190 was activated to transport sand and rock to the discharge boot 150. Rock, sand and grout they were fed through the discharge boot 150 and into the drum or cylinder of the concrete mixer truck. After the batch was completed, the desired and actual quantities of each component were compared. The results of this example are reported in Table 1 TABLE 1 Target Material Real Error Water Concentration (pounds) (pounds) of Moisture (pounds) Sand 15340.8 15.339.9 0% 2.0% 306.8
TABLE 1 (continued) Material Objective Real Error Concentration Water (pounds) (librais) of Moisture (pounds)
Rock 17786.1 17.879.9 +0.5% 1.0% 178.8 Cement 5.170.0 5,200.0 +0.6% Added 40.0 40.0 0% Water 2,273.1 2,282.0 +0.4%
The total weight of the components used in this example was 33,219.8 pounds. The total weight of water used in this example was 2,767.64 pounds. The total weight of cement used in this example was 5,200.0 pounds. The water to cement ratio in this example was
0. 532. The percent error of each of the components used in this example was less than 0.6 weight percent. The premellated concrete was found to exhibit a 6-inch subsidence. The air concentration was measured to be approximately 1.9 percent. The premixed concrete prepared in this example was allowed to cure to evaluate the strength of the concrete. After allowing the sample to cure for seven days it was found that the compressive strength of the concrete is approximately 3,630 pounds per square inch. After leaving the sample to cure for 28 days, the compressive strength was measured for two
The components used in this example were less than 0.5 weight percent. The ready-mixed concrete was found to exhibit a sink of 7.25 inches. The air concentration was measured to be about 1.8 percent. The premixed concrete prepared in this example was allowed to cure to evaluate the strength of the concrete. After leaving the sample heal for seven days, the compressive strength of the concrete was found to be approximately 5,370 pounds per square inch. After leaving the sample to cure for 28 days, the compressive strength was measured for two samples and found to be approximately 7,480 and 7,480 pounds per square inch. It is contemplated that the features described in this application, as well as those described in the above applications incorporated by reference, may be mixed and matched to suit the particular circumstances. Various other modifications and changes will be evident to those ordinary experts,